Laundry System Evaluation

The performance of different machines or chemical systems either within the one organisation or between organisations is facilitated by strictly controlled comparative trials. The techniques are also applicable to laundries which are required to comply with prescribed standards for contractual purposes.

The objective of any laundry is to produce acceptable visual and bacteriological results with minimal damage to the textile product. Textiles are susceptible to mistreatment which can significantly reduce their useful life and therefore increase replacement costs. The technique evaluates the ability of the laundering process to clean and the level of degradation occurring during multiple washings.

Principle

Standard control fabrics are supplied by AWTA Product Testing. These are laundered with regular soiled loads in the typical system used in day to day practice. External supervision or auditing of the trials is available on request.

The laundered control cloths are carefully protected and returned to AWTA Product Testing for further testing and an objective report.

Due to the possibility of minor differences in technique and equipment particularly with respect to reflectance measurements, results from one laboratory should not be compared directly with those from another laboratory.

Properties Evaluated

(a) EMPA Style #105 [5 Swatches - Bleach/Carbon Black, Mineral Oil/Blood/Cocoa/Red Wine]. The swatches are washed once and immediately dried. The following properties evaluated and reported:

- whiteness (with/without UV)

- intrinsic greying

- intrinsic yellowing

- percentage soil removal of the 4 types on the test swatch

(b) Textile (cotton) degradation and colour evaluation after extended washing.

EMPA Style #224 Tensile Strength Laundering Fabric. Test cloth is washed and dried 50 times and/or 25 times with the wash load being evaluated. The following properties are then evaluated on a sample of the unwashed swatch and on the washed swatches:

- tensile strength loss = total damage

- cuprammonium fluidity increase = chemical damage

- mechanical damage = difference between total & chemical damage

- increase in incrustation (ash content)

- whiteness (with/without UV)

- intrinsic greying

- intrinsic yellowing

Referenced Standards

ISO 2267 Surface active agents - evaluation of certain effects of laundering. Methods of preparation and use of unsoiled cotton control cloth.

ISO 4312 Surface active agents - evaluation of certain effects of laundering. Methods of analysis and test for unsoiled cotton control cloth.

ASTM D3050 Standard method for measuring soil removal from artificially soiled fabrics.

AS 2001.2.3 Physical tests - determination of breaking force and extension of textile fabrics.

AS 2001.3.6 Chemicals tests - determination of cuprammonium fluidity of cotton and cellulosic manmade fibres.

Materials Used

For each evaluation ISO 2267 recommends the use of the following:

- EMPA Article NO. 105 Artificially soiled swatch strip (IEC 456, amendment No.1)

- EMPA Article No.224 Unsoiled cotton control cloth (ISO 2267)

While it is tempting to use only one of each type of swatch for economy reasons, AWTA Product Testing recommends adherence to the ISO guide lines. That is 3 swatches per test. Testing costs will certainly not be reduced to one third due to economics and efficiencies of multiple handling. There is always the chance that an accident in the laundry can abort weeks of work. The risk of destroying all three swatches is considerably less than that of destroying one.

Control values on the EMPA Style #105 Swatches have been determined by AWTA Product Testing on each batch of imported swatches. Charges levied for the supply of these swatches include an allowance for the control testing.

When swatches are obtained from other sources and evaluation of the test results is requested, it is required that control swatches (preferably 3 of each type as required by ISO) are also submitted by the client for control testing.

Laundering Program

1. Soil Removal and Whiteness Retention Tests:

Each swatch must be laundered once with a typical load of laundry. To ensure the swatch can be found readily it is recommended that a colour-fast coloured marker cloth be sewn or otherwise firmly attached with non-corrosive fasteners along the long side of the strip. Mark an identification code on one edge of the white section.

When adding the swatch to the load, try to ensure it does not become twisted or the soil removal may be too uneven to be meaningful.

Retrieve the swatch before the final drying operation and air dry it immediately. Fold along the junction of the test pieces and place the swatch in a clear plastic bag for protection.

2. Textile Degradation Test:

The EMPA #224 swatches are laundered in separate parts of the same load. They have a coloured marker attached which makes them easier to find at the end of each wash, dry and ironing cycle. At the completion of each cycle an indelible mark is made on the test piece to record the number of completed cycles.

It is recommended that 50 cycles be conducted before testing, although when 25 wash and dry cycles have been completed, each swatch may be cut in half along the centre green stripe such that the portion without the cycle marks is removed. The remaining half should be hemmed along the cut edge and returned for a further 25 washes.

The 25 cycle swatches should be lightly pressed to remove creases, marked appropriately for identification and placed in a clean plastic bag for transmittal to the laboratory.

The same procedure is repeated after 50 cycles have been completed.